The "good" argument is that people trust other people's opinion more who have not been paid to advertise. I trust the doctor who personally recommends a drug more than the doctor who was paid to recommend the drug - even if they recommended the drug before they were paid. That's a fact of life, it's not "character assassination". Tao didn't do anything wrong by making an ad but he can't expect people to take his opinion seriously after someone gave him a lot of money to state an opinion that favors them.
It's proper to suspect arguments that are motivated by self-interest. The stronger that self-interest, the more one should suspect the argument. This is what you're saying?
In that case, the anti-AI Luddite arguments are maximally impeached, since they are motivated by fear of personal disaster. Tao doesn't need AI to succeed; the Luddites desperately need it to fail. So they are willing to say anything, jumping right to ad hominem arguments when they lack any real substantive rebuttal.
I don’t know that Terry much cares about the opinions of people who judge claims based on innuendo and cynicism rather than the actual merits of the claim.